They are really good in all curries. You can leave them whole if you are making a dish that is not smooth or grind them or crush in a mortar and pestle. They also add a good flavour to Coleslaw, add crushed to meat rubs for BBQ's. Also good anything with cheese! Use sapringly, the flavour is strong.
Dry roast them in a pan before use to enhance the flavour and nearly forgot to tell you that they are a digestive so add to bean and lentil dishes. They work well in carrot dishes, in fact if you make anything where you would use cumin, ajwain will work well.
Carrot soup with garam masala and ajwain is delicious!
I'm trying to thing how to explain the flavour, a little stronger than thyme, a bit bitter and peppery.